Known wind turbines, in their conventional construction, have a tower, on the upper end of which a generator with a generator housing is arranged. A rotor, which typically bears three rotor blades, is connected to the generator directly or via a transmission. To adapt the position of the rotor blades to different wind speeds, the rotor blades are attached to the rotor so as to be rotatable about a rotor blade longitudinal axis. For this purpose, axial-radial large rolling bearings are used as blade adjustment bearings (Erich Hau, “Windkraftanlagen—Grundlagen, Technik, Einsatz, Wirtschaftlichkeit” [“Wind Turbines—Fundamental Principles, Technologies, Application, Economics”], 2nd Edition, 1996, pages 233-234). It is the object of said bearings and of an associated adjustment arrangement to adapt the angle of incidence of the associated rotor blade to the respective wind speed and/or to the operating state of the turbine.
DE 10 2011 000 769 A1 has disclosed an axial-radial rolling bearing which is suitable in particular for the mounting of rotor blades on a wind turbine and which, while being of compact design, is characterized by a high load-bearing capacity. For radial support, a radial bearing row is arranged in the conventional manner between an inner ring and an outer ring.
With regard to the radial support, cylindrical roller bearings of similar construction are known from DE 30 34 008 C2 and from EP 0 413 119 B1. The radial mounting is realized by way of a radial bearing row which is arranged between an inner ring and an outer ring. One of the bearing rings comprises a groove which is open in a radial direction. If this is the outer ring, the groove is open in the inward radial direction toward the axis of rotation. By contrast, if the inner ring is provided with the groove, said groove is open in the outward radial direction. The respective other bearing ring has a lobe which engages into the groove. Such a ring is in practice also referred to as lobe ring. The first radial bearing row is arranged on a radially encircling tip of the lobe, whereas two axial bearing rows which are spaced apart in an axial direction are provided on the lateral flanks of the lobe. In the case of such a construction, the inner ring is supported in the outward direction against the outer ring by way of the radial bearing row.
Depending on the use of the cylindrical roller bearing, considerable forces may arise, which may to a certain extent also cause a deformation of the bearing and/or of the interacting bearing rings. Specifically in the case of blade adjustment bearings, it is possible, if the connecting structure is of inadequate rigidity, for the forces that occur during operation to elastically deform the bearing rings such that they no longer have a circular shape. This deformation which occurs under load is also referred to as ovalization. In the case of a conventional cylindrical roller bearing with only one radial bearing row, such a deformation may cause the inner ring to locally move away from the outer ring, such that at said circumferential section, the cylindrical rollers as rolling bodies no longer contribute to a supporting action, whereas increased distortion and compressive loads arise in other regions of the circumference.
In order to realize a more uniform force distribution and counteract the described deformation of the bearing rings, a cylindrical roller bearing as disclosed in EP 2 092 204 B1 was developed. One of the two bearing rings comprises a lobe ring, wherein the other bearing ring has a projection which engages around the lobe ring. This permits a design in which the lobe ring is guided not only in the axial direction but also in the radial direction by in each case two opposite rows of cylindrical rollers. Owing to the bilateral guidance, the rings can no longer be deformed differently to one another in a radial direction, such that the overall construction is characterized by an increased strength, wherein the bearing rings also cannot regionally move away from one another in the radial direction.
It is however a disadvantage that, in particular in the radial direction, a considerable amount of installation space is required for the arrangement of the lobe ring.
Against this background, the problem addressed by the present invention is that of specifying a cylindrical roller bearing in which different deformation of the interacting bearing rings in a radial direction is avoided, while at the same time a compact design is realized.